The cover of the invention relates generally to a cover used in a medical treatment environment to control the bodily temperature of a patient, and more specifically to such a cover which controls the temperature of a covered patient's body by bathing it with a temperature controlled gas mixture.
It is often the case that the bodily temperature of a patient who is about to undergo or who has undergone certain forms of medical treatment such as surgery must be regulated by lowering or elevating it to a predetermined average level. In existing apparatus, the generalized control of such a patient's temperature is provided by means of a pliable blanket through which a temperature controlled fluid is circulated. When the patient is covered with such a blanket, the temperature of the fluid is conducted to the patient to move the patient's temperature toward the desired level. However, most of the temperature exchange between the blanket and the patient takes place only at the points where the blanket contacts the patient's skin. This can result in localized thermal activity of a high rate where the blanket and the patient's skin are in contact, which results in the localized temperature of the contacted portion of the patient's body being either substantially above or below the desired average temperature. When the patient's body temperature is being elevated and the circulating fluid is heated, this can result in burning at the contacted areas. In addition, the heat transfer between the blanket and the portions of the patient's body which the blanket does not contact is radiative and therefore inefficient.
In other covers, the circulating heat transfer mechanism is temperature controlled air. In one such cover disclosed in U.S. Pat. No. 2,110,022, the air is circulated inside of a flexible bag which has a top insulating layer and a bottom heat conducting layer which contacts the patient. However, the structure of this blanket makes it unnecessarily heavy and rigid. The weight of the blanket can press its inner surface against the covered patient and block a number of the exit ports, thereby reducing the total body area over which the air circulated.
It is therefore desirable to provide a supple, lightweight cover for efficiently and effectively controlling the bodily temperature of a covered patient.